DIN 939 Standard
DIN 939 is the German industrial standard for tap-end stud bolts (Stiftschraube) with a screw-in length of 1.25 × d, where d is the nominal thread diameter. Originally issued in 1937 and last revised in 1986, it covers metric coarse-thread studs in sizes M3 through M68 and metric fine-thread variants from M8×1 through M52×3, manufactured to tolerance class 6g per ISO 965 on the nut end and to interference-fit class Sk6 per DIN 13-50/-51 on the tap end.
DIN 939
Standard specifies dimensions and technical delivery
conditions of studs intended for use mainly in stainless steel, carbon
steel and alloy steel with a comparatively lower demand in brass as
well. Din 939 Tap End Studs have a thread length
engagement equal to 1.25d on stud end and the nut end length varies as
per the application. Tap End Stud bolts can be manufactured as per
DIN 939 Specification with metric thread M3 to M52 and metric
fine thread M8x1 to M52x3. As specified in DIN 267-2, the tap end studs
shall be produced to tolerance Sk6 as in DIN 13-51, unless the stud is
designated without interference - Fit Thread (Fo) or Sn4.
When ordering DIN 939 Tap End Studs, the correct dimension is
diameter x nominal length (excluding the tap end b1).For example, with a
stud measuring M10X75 (the diameter(d) = 10mm and nominal length(l) = 75
mm where the thread length on the metal end (tap end) b1 = 12 mm; the
overall length of the stud is 75 + 12 = 87 mm. The thread length on the
nut end b2 varies depending on the length of the stud as illustrated in
the table above.
